1. Field of The Invention
This invention generally relates to a channel assigning device for use in an electronic musical instrument, and more particularly, to a channel assigning device by which a most appropriate channel assigning processing can be performed.
2. Description of the Related Art
As a conventional channel assigning device for use in an electronic musical instrument, there is known a device employing a channel pointer which assigns musical tone information to a channel by serially searching channels subsequent to the channel indicated by the channel pointer, to determine whether or not a channel is in the KEY OFF state, i.e., is turned off, when an operation of sounding musical tones is to be carried out. Further, this conventional channel assigning device has been improved to provide a device which stores the order in which keys are turned on and off for every channel, in place of the above-mentioned channel pointer, and assigns musical tone information to a channel on the basis of the thus stored order.
Recently, however, an electronic musical instrument which can generate and sound various musical tones having different envelopes by using only one keyboard has been developed, wherein some of the various envelopes begin decaying even while a key is being pressed and some do not decay until the pressed key is turned off.
Therefore, where musical tone information is assigned to channels on the basis of the order in which keys are turned on or off, as in the conventional musical instrument, the musical tone information on a musical tone having a smallest envelope cannot be preferentially supplied to a channel, and further, the musical instrument generating such a musical tone cannot be assigned a channel. Thus, the conventional devices cannot assign musical tone information to a channel which is most appropriate for the sounding of each musical tone.
The present invention is intended to eliminate the above described defect of the conventional device, and accordingly, an object of the present invention is to provide a channel assigning device for use in an electronic musical instrument and which can assign musical tone information to a channel which is most appropriate for the contents of the envelopes.
Further, in a conventional channel assignment system, when a keyboard is composed of a plurality of keyboard components such as an upper-keyboard, lower-keyboard, solo-keyboard, and pedal-keyboard, key scanning processing, key assigning processing, and channel assignment processing, are performed for each of the keyboard portions. This, however required regulation of the various processes, such as a mutual use of the system for performing the key scanning processing and the key assigning processing among the keyboards, which necessitates a determination of priorities of the keyboards, and therefore, the key scanning processing and the key assigning processing are very complex in the conventional channel assignment system.
Furthermore, in a MIDI (Musical Information Digital Interface) system, for example, when musical tone information is supplied from an external keyboard or the like, the system encounters similar problems, and thus another kind of key assigning processing is required for processing only MIDI musical tone information and a special stack must be dedicated to such key assigning processing. Note, the MIDI is a specification of a communications scheme for digital music devices, and accordingly, the term "MIDI musical tone information" indicates musical tone information generated in accordance with the MIDI specification.
The present invention is also intended to eliminate these drawbacks of the conventional channel assigning system.
Therefore, another object of the present invention is to provide a channel assigning device for use in an electronic musical instrument, by which a most appropriate channel assignment can be obtained by effecting a simple key scanning and assigning processing and by using circuits having a simple structure.
Furthermore, in the conventional channel assigning system, when musical tone information is assigned to all channels and another key is pressed, the earliest musical tone information, determined on the basis of the order in which keys are pressed or turned off, among the musical tone information already assigned to channels at that time is released at high speed, thereby forcibly terminating the sounding of the musical tones and assigning new musical information to the channel to which the thus released musical instrument had been assigned.
When the envelope level is instantly lowered to "0" by such a high speed release, the sounds are generated as noise. This is prevented by delaying the release of the earliest musical tone information to an extent such that noise is not produced. Therefore, during the high speed release, the assignment of new musical tone information to a channel must be deferred, and this is very disadvantageous and places a heavy burden on the system in which the key assigner is composed of microcomputers or the like.
As a means of resolving this problem, it has been proposed that, even during the high speed release, new musical information be assigned to the channel in question, whereby the above described problem of deferring the assignment of new musical tone information is solved, and further, the assignment of musical tone information to channels can be effected at a high speed. Nevertheless, this leads to another problem in that, after the high speed release, the pitch and timbre of a musical tone is changed, and accordingly the quality of the musical tone is also changed.
The present invention is also intended to eliminate these defects of the conventional channel assigning system.
Therefore, still another object of the present invention is to provide a channel assigning device for use in an electronic musical instrument and which can immediately assign musical tone information corresponding to the musical tone, the sounding of which is newly issued, to a channel, and the content of the musical tone information assigned to this channel by that time is not changed until the sounding of the corresponding musical tone is terminated even when musical tone information is assigned to all channels, to thereby obtain the most appropriate channel assignment.